Node.js Socket.IO

Node.js Socket.IO

1. Eyal Vardi Microsoft MVP ASP.NET blog: eyalvardi.wordpress.com Socket.IO

2. Agenda Type of Communications WebSocket Socket.IO Angular Socket.IO

3. Type of Communications

4. Periodic polling Poll from time to time using Ajax Delay in communications due to polling interval Wastes bandwidth & latency  Polling interval Client Server

5. Long polling Poll but don’t respond untill there’s data Poll again after data received or after the connection times out. Consumes server threads & connection resources  Client Server

6. HTTP/1.1 200 OK Content-Type: text/plain Transfer-Encoding: chunked Forever Frame Server tells client that response is chuncked Client keeps connection open untill server closes it Server pushes data to the client followed by \0 Consumes server threads. Client <script> eval ("... ")</script>\0 <script> eval ("... ")</script>\0 Server

7. WebSockets

8. What is WebSockets ? WebSocket is a web technology providing for bi-directional, full-duplex communications channels over a single TCP connection . The communications are done over the regular TCP port number 80 or 443. ws:// and wss:// prefix to indicate a WebSocket and a WebSocket Secure connection, respectively.

9. WebSocket Protocol Handshake To establish a WebSocket connection, the client sends a WebSocket handshake request, and the server sends a WebSocket handshake response. HTTP/1.1 101 Switching Protocols Upgrade : websocket Connection : Upgrade Sec- WebSocket -Accept : HSmrc0sMlYUkAGmm5OPpG2HaGWk= Sec- WebSocket -Protocol : chat GET / mychat HTTP/1.1 Host : server.example.com Upgrade : websocket Connection : Upgrade Sec- WebSocket -Key : x3JJHMbDL1EzLkh9GBhXDw== Sec- WebSocket -Protocol : chat Sec- WebSocket -Version : 13 Origin : http://example.com Client Server

10. WebSocket Protocol Handshake WebSocket data frames can be sent back and forth between the client and the server in full-duplex mode. Both text and binary frames can be sent in either direction at the same time. The data is minimally framed with just two bytes. In the case of text frames, each frame starts with a 0x00 byte, ends with a 0xFF byte, and contains UTF-8 data in between. WebSocket text frames use a terminator, while binary frames use a length prefix.

11. HTML5 WebSocket API var myWebSocket = new WebSocket (" ws ://www.websockets.org "); myWebSocket.onopen = function( evt ) { alert("Connection open ..."); }; myWebSocket.onmessage = function( evt ) { alert (" Received Message: " + evt.data ); }; myWebSocket.onclose = function( evt ) { alert("Connection closed."); } myWebSocket.send ("Hello WebSockets !"); myWebSocket.close ();

12. Web Socket Echo (http :// www.websocket.org/echo.html)

13. Socket.IO

14. Socket.IO Socket.IO enables real-time bidirectional event-based communication . It works on every platform , browser or device , focusing equally on reliability and speed . Samples: Real-time analytics Binary streaming Instant messaging and chat Document collaboration

15. Echo Sample (Server) var http = require( "http" ); var connect = require( "connect" ); var socketio = require( "socket.io" ); var app = connect(); app.use ( connect.static ( "public" )); var server = http.createServer (app); var io = socketio.listen (server); io.on ( "connection" , function (socket) { socket.on ( "message" , function (data) { socket.emit ( "echo" , data); }); }); server.listen (8000);

16. Echo Sample (client) < !DOCTYPE html > < html > < head > < script src ="/socket.io/socket.io.js"></ script > </ head > < body > < body > < script > var socket = io.connect( "http://localhost" ); socket.emit ( "message" , "Hello!" ); socket.on ( "echo" , function (data) { document.write (data); }); </ script > </ body > </ html >

17. Broadcasting In order to send an event to everyone, Socket.IO gives us the io.emit : io.emit ( 'some event' , { for : 'everyone' }); socket.broadcast.emit ( 'some event' );

18. Chat

19. Namespaces Socket.IO allows you to “namespace” your sockets, which essentially means assigning different  endpoints   or paths . We call the default namespace / and it’s the one Socket.IO clients connect to by default, and the one the server listens to by default. // Server Side var nsp = io.of ( '/my-namespace' ); nsp.on ( 'connection' , function (socket) { console.log( 'someone connected' ); }); nsp.emit ( 'hi' , 'everyone!' ); // Client Side var socket = io ( '/my-namespace' );

20. Rooms Within each namespace, you can also define arbitrary channels that sockets can join and leave. io.on ( 'connection' , function (socket) { socket.join ( 'some room' ); }); io.to( 'some room' ).emit( 'some event' );

21. Integration With AngularJS Socket.IO integration with any JavaScript application should be simple enough. In Angular, there are a few subtleties to address, such as the digest cycle . Angular-socket- io by Brian Ford is a tiny and simple bower component that takes care of those issues +

22. Using angular-socket- io Using Your Socket Instance. var mi = angular.module ( ' myApp ' , [ ' btford.socket-io ' ]); mi.factory ( ' mySocket ' , function ( socketFactory ) { return socketFactory (); }); mi.controller ( ' MyCtrl ' , function ( mySocket ) { // ... });

23. Using angular-socket- io angular. module ( ‘ socketioApp ' ) . controller ( ' MainCtrl ', function($ scope, socket ) { } socket. forward (‘my-event', $scope); $ scope. $on ( ‘ socket: my-event ' , function (event, serverData ) { $ scope.data = serverData ; }); socket . emit (‘event-from-client’, someData ) Allows you to forward the events received by Socket.IO's socket to AngularJS's event system. 

24. Thanks eyalvardi.wordpress.com Eyal Vardi Microsoft MVP ASP.NET blog: eyalvardi.wordpress.com